Sealed assembly for separation of blood components and method

ABSTRACT

A self-contained fluid separator assembly is disclosed capable of separating blood into its component parts of plasma or serum, the light phase, and the cellular portion, the heavy phase. The assembly comprises a container having at least one open end for receiving blood for subsequent separation and a closure sealing the open end of the container, the closure being formed of a self sealing elastomeric material which is penetrable by a pointed hollow needle through which the blood to be separated is conducted into the container. A piston is slidably disposed in the container with its outer surfaces in sealing contact with the inner surfaces of the container. Pressure responsive valve means is provided on the piston which is normally closed when there is a minimum pressure differential on each side of the piston and the valve automatically opens in response to a substantial pressure differential so that when the container is subjected to centrifugal force the blood first separates into its light phase and heavy phase and the valve means automatically opens with the light phase passing through the valve means and the piston moves down through the light phase while retaining sealing engagement with the inner surfaces of the container. Positive stop means is provided on the container between its ends so that the piston as it moves through the light phase will contact the stop means and stop at a predetermined distance above the closure bottom of the tube means whereupon the pressure differential is terminated and the valve means automatically closes to provide an impervious barrier between the separated light and heavy phases of the blood.

United States Patent Ayres Dec. 18, 1973 SEALED ASSEMBLY FOR SEPARATIONOF BLOOD COMPONENTS AND METHOD Inventor: Waldemar A. Ayres, Rutherford,

Becton, Dickinson and Company, East Rutherford, NJ.

Filed: Apr. 25, 1972 Appl. No.: 247,386

[73] Assignee:

210/109, DIG. 23, 514-518 References Cited UNITED STATES PATENTS 4/1970Coleman 2l0/DlG. 23

5/1972 Greenspan t 210/359 4/1942 Riachall 210/518 5/1895 Shugerman210/515 9/1972 Grover 210/359 Primary Examiner.lohn Adee Attorney-DavidS. Kane et al.

[57] ABSTRACT A self-contained fluid separator assembly is disclosedcapable of separating blood into its component parts of plasma or serum,the light phase, and the cellular portion, the heavy phase. The assemblycomprises a container having at least one open end for receiving bloodfor subsequent separation and a closure sealing the open end of thecontainer, the closure being formed of a self sealing elastomericmaterial which is penetrable by a pointed hollow needle through whichthe blood to be separated is conducted into the container. A piston isslidably disposed in the container with its outer surfaces in sealingcontact with the inner surfaces of the container. Pressure responsivevalve means is provided on the piston which is normally closed whenthere is a minimum pressure differential on each side of the piston andthe valve automatically opens in response to a substantial pressuredifferential so that when the container is subjected to centrifugalforce the blood first separates into its light phase and heavy phase andthe valve means automatically opens with the light phase passing throughthe valve means and the piston moves down through the light phase whileretaining sealing engagement with the inner surfaces of the container.Positive stop means is provided on the container between its ends sothat the piston as it moves through the light phase will contact thestop means and stop at a predetermined distance above the closure bottomof the tube means whereupon the pressure differential is terminated andthe valve means automatically closes to provide an impervious barrierbetween the separated light and heavy phases of the blood.

17 Claims, 5 Drawing Figures SEALED ASSEMBLY FOR SEPARATION OF BLOODCOMPONENTS AND METHOD BACKGROUND OF THE INVENTION It is known toseparate blood into its component parts by jentrifugation particularlyemploying a sealed containe such as is disclosed in U.S. Pat. No.2,460,641. This patent discloses a container having a closure at itsopen end which is capable of being penetrated by a pointed hollow needlethrough which blood passes into the container. The clinical laboratorieshave used this device to collect a blood sample for subsequent searation intq a light phase, i.e., the serum or plasma, and the heavyphase, i.e, the cellular portion. The light phase is then decanted fromthe cellular portion by any conventional means, for example, the use ofa syringe fitted with a cannula or a pipette or the like. 1

An apparatus also employed for the separation of blood is disclosed inU.S. Pat. No. 3,508,653. This patent discloses a self-containedassembly, having a stopper, for separation of body fluid such as bloodin which a deformable piston is disposed in the container and ispositioned initially adjacent the stopper. After the container is filledwith blood the assembly is centrifuged and the blood is separated intoits light and heavy phases. Then, increased centrifugal force is appliedto the container, the seal between the inner glass surface of thecontainer and piston is broken, the piston is deformed and moves downthrough the light phase with the light phase passing upward solelybetween the outer surfaces of the piston and the inner surfaces of thecontainer. When the piston reaches the interface between the light phaseand the heavy phase, the piston movement is stopped, the force isterminated, and the seal is re-established between the inner surface ofthe glass container and the resilient piston to establish a barrierbetween the two phases. Other devices known to the art are generally thefiltration device which separates blood into its component phases suchas disclosed in U.S. Pat. Nos. 3,481,477 and 3,512,940.

SUMMARY OF THE INVENTION The invention generally contemplates theprovision of a self-contained sealed fluid separator assembly capable ofseparating blood into its component parts of plasma or serum as thelight phase and the cellular portion as the heavy phase and establishinga sealed barrier therebetween without the necessity of opening thecontainer or decanting the separated light phase from the heavy phase.

It is an object of the invention to automatically separate blood intoits component phases by simply subjecting the self-contained assembly tocentrifugal force so that upon completion of the centrifuging operationan impervious barrier separates the light phase from the heavy phase of.the blood. The assembly is capable of withstanding rough handlingthrough the mails, inversion of the container without remixing thecomponent phases and preventing various chemical constituents in thelight phase from leaking into'and mixing with the heavy phase or viceversa. It is also an object of the in- 'vention to provide an assemblywhich is adapted for use on conjunction with other blood samplingdevices for obtaining samples to be centrifuged without the necessity ofemploying special equipment. Another object, in

an alternative form of the invention is topass the light phase of theblood through a filter associated with the pressure responsive valvemeans. It is a further object of the invention to provide aself-contained assembly for separating blood into its component partswhich is inexpensive to manufacture, simple to assemble and easy to use.t

The separator assembly for separating blood into its component parts ofplasma or serum, the light phase, and cellular portion, the heavy phase,is a selfcontained unit which requires only that a sample of blood to beseparated be provided within the container. The container is formedhaving at least one open end which is adapted to receive blood forseparation into its component phases. A closure is mounted in the openend for sealing the container, this closure being formed of aself-sealing elastomeric material which is penetrable by a pointedhollow needle through which blood to be separated is conducted into thecontainer. A piston is slidably mounted in the container having itsouter cylindrical surfaces in sealing engagement with the inner surfacesof the container. Pressure responsive valve means is disposed on saidpiston and is normally closed when there is a minimum of pressuredifferential on the two sides of the piston. The valve meansautomatically opens in response to a substantial pressure differentialso that when the container is subjected first to moderate centrifugalforce, the blood separates into its light phase and heavy phase and whenthe centrifugal force is substantially increased thereafter the valvemeans automatically opens with the light phase passing up through thevalve means while the piston moves down through the light phase and thepiston retains its sealing engagement with the inner surfaces of thecontainer. A stop means is formed on the container and disposed apredetermined distance from the bottom of the container which is remotefrom the piston in its initial position so that the piston when movingthrough the light phase is caused to stop when it reaches the stopmeans; the pressure differential is terminated and the valve meansautomatically shifts from the open position to the closed position toprovide an impervious barrier between the separated light phase andheavy phase of the blood. Thereafter, the centrifuging is terminated andthe separated sample is ready for subsequent testing.

For a better understanding of the invention reference is had to thedrawings which illustrate the preferred embodiments of the inventionherein.

FIG. 1 is a sectional elevational view of the separator assemblyillustrating a pointed cannula penetrating one of the closures throughwhich blood is introduced into the container prior to separation.

FIG. 2 is a view similar to FIG. 1 illustrating the separation of theblood into the light phase and heavy phase with the piston engaging thestop means.

FIG. 3 is an end view of the assembly of FIG. 1 as viewed from the top.

FIG. 4 is a sectional view taken along the lines 44 of FIG. 2.

FIG. 5 is a fragmentary sectional view of the container of FIG. I havinga modified piston with filter mounted therein.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding ofthe invention herein a description of the drawings of the illustrativeembodiments is had, particularly with respect to the embodiments shownin FIGS. 1 through 4.

In FIG. 1, the separator assembly comprises a tubular member orcontainer 12 having mounted in each of the open ends 11 and 15 closures14 and 16. C10- sures l4 and 16 are made of a self-sealing elastomericmaterial such as rubber. Closure 16 is capable of receiving cannula l8penetrated therethrough as illustrated in FIG. 1 for conducting bloodinto the container. When the cannula is removed the closure is resealedwith no loss of blood passing through the penetration portion asillustrated in FIG. 2.

Closure 14 is formed having a depending cylindrical body portion 20 anda flanged head portion 22 integrally formed therewith. Body portion 20has a diameter slightly greater than the internal diameter of thecontainer 12 so that closure 14 when mounted into end 11 provides aninterference fit to seal the end. Head portion 22 is shaped in the formof a hexagon (as shown in FIG. 3) and is slightly greater in diameterthan body portion 20 which permits the assembly to be positioned on itsside without danger of rolling.

Stopper 16 has a cylindrical body portion 28 and an integrally formedcylindrical head portion 30 having an axial recess 24. Body portion 28has an annular recess 29 to provide a self-sealing penetrable zone 31 tofacilitate insertion of cannula or pointed hollow needle 18 with minimumforce while maintaining a sealed closure. As noted above, stopper orclosure 14 as well as 16 is inserted into ends 11 and 15 in compressionto maintain ends 11 and 15 of container 12 in sealed gas tightengagement.

Tubular member or container 12 is formed preferably of glass but anyother suitable material may be employed. Intermediate ends 11 and 15 oftubular member 12 is an annular groove 32 which forms a stopconstriction means 34 as a part of the inner surfaces of container 12.Thus, as piston 40 moves from the initial starting position illustratedin FIG. 1 to the terminal position after the separation of the lightphase from the heavy phase as shown in FIG. 2, the piston comes to restat the stop means 34 formed by annular groove 32 of container 12. It isnot necessary to take special precautions concerning the density of thepiston with respect to the density of the blood, provided the piston hasgreater specific gravity, since the piston will autmatically come torest at stop means 34 when the increased centrifugal force is applied tothe assembly. The seal of the piston with respect to the inner surfacesof the container is constant throughout its travel from its initialposition of FIG. 1 to its terminal position of FIG. 2.

Piston 40 comprises a tubular metal insert 52 which is mounted inannular recess 54 of piston 40. Metal insert 52 is preferably made ofstainless steel or other rigid, chemically inert material having aspecific gravity substantially greater than blood. Piston 40 is formedof elastomeric material and is provided with annular re cess 54 which isdimensioned to receive tubular member 52in an interference fit so thatno air space remains in annular recess 54.

The elastomeric portion of piston 40 comprises an outer wall 48 andspaced therefrom is inner wall 46 in which their respective wallsurfaces define annular recess 54. Formed integrally with wall 48 are aplurality of radially spaced resilient sealing rings 50 which contactthe inner wall surface 13 of container 12 in sealing engagement. Piston40 when mounted in container 12 will maintain sealing contact with innerwall 13 of container 12 throughout its path of travel within container12. During the centrifuging operation when increased speed is usedpiston 40 is subjected to centrifugal forces which start to move itdownwardly. This movement establishes a pressure differential on the twosides of the top wall or diaphragm portion 44 of piston 40. Thediaphragm 44 is made of relatively thin, stretchable or resilientmaterial and lies adjacent and against stopper 14 in its initialposition as seen in FIG. 1. Diaphragm 44 is made of a resilient materialand is provided with a plurality of normally closed apertures 42extending therethrough. Wall portion 46 of piston 40 defines an axialannular recess so that as the assembly is being subjected to increasedcentrifugal force the light phase which is separated from the blood willpass into annular recess 80. Also, since the centrifugal force acting onpiston 40 will generate a force greater than the force of the lightphase being exerted against the diaphragm 44 apertures 42 willautomatically open and will enable the light phase liquid to passupwardly through the opened apertures and enable piston 40 to move fromits initial position of FIG. 1 to its final position of FIG. 2 whilemaintaining sealing engagement with the inner wall 13 of container 12.When piston 40 stops its movement in container 12 and comes to rest onstop means 34, the fluid pressure differential on the two sides ofdiaphragm 44 is substantially eliminated and aperture valve means 42automatically closes even though the assembly is being subjected tocentrifugal forces.

Piston 40 as noted above includes tubular insert 52 which is mounted inthe annular recess 54 with an interference fit with no air spacetherearound. Also, when piston 40 is subjected to centrifugal forces theradial outward thrust force of the increased pressure of the liquid inrecess is restrained by tubular insert 52 and will not be transmitted toresilient sealing rings 50 which would cause a major increase offriction between the piston 40 and the interior of glass tube 12 so thatpiston 40 may be prevented from sliding down to stop 34. Tubular insert52 as noted above has such a specific gravity that it, plus theelastomeric piston together, have a specific gravity greater than bloodand when subjected to-centrifugal forces provide a large downwardthrust, more than sufficient to overcome the friction of the multipleseal rings 50 of the piston relative to the glass tube plus the addedwork of opening the resilient aperture valve meansv The elastomericportion of piston 40 is preferably made of rubber.

As illustrated in FIG. 2, piston 40 has completed its travel withincontainer 12 and is stopped from further movement in container 12 bystop means 34 and valve means 42 are closed. Also, a portion of thelight phase remains above the separated heavy phase and is not utilizedas part of the separated light phase.

In FIG. 4 the top plane of piston 40 is shown at its position at stopmeans 32. Resilient seal ring 50 is shown in sealing engagement withwall 13 of container 12 with walls 46 and 48 of piston 40 defining theannular recess for tubular insert 52. At the central portion of piston40 is diaphragm 44 and apertures 42 in the open position whichillustrates the automatic valve means formed in piston 40 in the openposition even though centrifuging is being continued.

Referring now to the embodiment illustrated in FIG. 5 which illustratesan optional alternative form of piston 40 which provides filter element60 mounted in annular recess 80. In all respects in FIG. 5, thecontainer 12, closure 14 and piston 40 are identical to FIG. 1 and allcorresponding parts are similarly numbered. Filter 60 may be made of anysuitable filter material chemically inert to blood and capable offiltering serum or plasma. Such a material may be asbestos or glasswool, a plastic foam having interconnecting passages, paper or othersuitable fibrous or particulate material. The main purpose for employingfilter 60 is to remove any fibrin or partially formed fibrin materialfrom passing through valve means 42.

When operating the separator assembly of the invention herein it ispreferred that the assembly be evacuated so that when cannula l8penetrates closure 16 blood will fill container 12 without requiring theuse of an air vent. It is also contemplated to provide a separatorassembly suitable for use with the blood collecting assembly disclosedin U.S. Pats. Nos. 2,460,641, 3,469,572 and 3,494,352. It is importantwhen filling the assembly 10 that blood be introduced into container 12through the stopper 16 mounted on the bottom of the container to obviatethe possibility of having blood cells trapped between the piston 40 andstopper 22 which will later separate to form the chamber where the lightphase will be collected thus contaminating the light phase with blood.If the assembly is evacuated it is obvious blood will fill the spacebetween closure 16 and the piston 40.

After cannula 18 is withdrawn and container 12 is filled with blood theassembly is placed in a centrifuge and the blood is separated initiallyemploying moderate centrifugal forces which do not cause the piston tomove from its initial position. This precipitates or separates the bloodcells or blood clot into the tube portion below constriction stop means34. Thereafter the rotational speed of the centrifuge is increased whichcauses a substantial downward thrust on the piston. As the piston startsto move it increases the hydrostatic pressure in the liquid ahead of itand stretches the diaphragm and valve means 42 automatically opens andthe piston moves downwardly through the light phase with the light phasepassing up through the valve means. Piston 40 maintains sliding andsealing engagement with the inner wall 13 of container 12. The pistoncompletes its movement when it engages stop means 34 and termihates thepressure differential at the bottom and top of the diaphragm andautomatically closes the resilient aperture valve means even while theassembly is still subjected to centrifugal forces as illustrated in FIG.4. Before centrifuging is terminated diaphragm 44 establishes animpervious barrier between the light and heavy phases of the blood whenvalve means 42 automaticaliy closes on piston 40.

Then centrifugal forces are terminated and the separated blood sample isready for use. As desired, the serum or plasma can be taken from one endand/or the concentrated red cells can be taken from the other end.

While variations of the invention herein may be had, the objectives ofthe invention have been illustrated and described.

I claim:

1. A self-contained fluid separator assembly, capable of separatingblood into its component parts of plasma or serum and cellular portion,comprising:

a. a container having at least one open end which is adapted to receiveblood for subsequent separation into a light phase and a heavy phase;

. a closure sealing the open end of the container, the closure beingformed of a self-sealing elastomeric material which is penetrable by acannula through which blood to be separated is conducted into thecontainer;

0. a piston having a specific gravity relatively greater than thecellular portion of the blood and slidably mounted in the container andhaving means on an outer surface in sealing engagement with an innersurface of the container;

d. pressure responsive valve means associated with said piston, saidvalve means being normally closed when there is a minimum of pressuredifferential on different portions of the valve means and whichautomatically opens in response to a substantial pressure differentialso that when said container is subjected to moderate centrifugal forcethe blood separates into its light phase and heavy phase but the pistonstays in the upper portion of the container, and subsequently whenincreased centrifugal force is used the valve means automatically openswith the light phase passing up through the valve means enabling thepiston to move down through the light phase while retaining sealingengagement with the inner surfaces of the container; and

e. mechanical stop means on the container whereby the piston when movingthrough the light phase will stop a predetermined distance from one ofthe ends of the container followed by termination of the differentialpressure which permits the valve means to automatically shift from anopen position to a closed position to provide an impervious barrierbetween the separated light phase and heavy phase of the blood. a

2. The self-contained fluid separa tor of claim 1 wherein the pistonincludes a rigid; tubular sleeve mounted in a generally tubular outerbody portion formed of an elastomer and having at least one sealing ringon its outer portion for sealing engagement with the inner walls of thecontainer and a diaphragm forming a wall across one end of the generallytubular elastomeric sleeve and having apertures formed therein which arenormally closed but which automatically open when subjected to asubstantial pressure differential on the opposite sides of thediaphragm.

3. The self-contained fluid separator of claim 1 wherein the stop meanson the container is an annular groove interposed between the ends of thecontainer forming an annular constriction of the inner surface of thecontainer so that said piston is prev nted from passing the stop meanswhen subjecte to centrifugal forces.

4. The invention in accordance with claim 1, wherein a plurality ofspaced annular sealing rings are on the periphery of the piston and insealing engagement with the interior of the container.

5. The invention in accordance with claim 1, wherein the valve means isindependent of the piston sealing means.

6. A piston adapted for use for separating fluid into a light phase anda heavy phase in a self-contained fluid separating assembly comprising:

a. a body portion having sealing means formed on its outer peripheralwalls for maintaining sealing engagement with the inner walls of thefluid separator assembly;

. a rigid tubular sleeve mounted in the body portion of said piston andhaving an interference fit and pressure responsive valve means mountedon the piston which is normally closed when there is a minimum ofpressure differential on the surfaces of the valve means and which opensautomatically in response to a substantial pressure differential so thatwhen the container is subjected to moderate centrifugal force the fluidseparates into its light phase and heavy phase and when the container issubjected to increased centrifugal force the valve means automaticallyopens with the light phase passing through the valve means enabling thepiston to move down through the light phase while retaining sealingengagement with the inner surfaces of the container, the rigid tubularsleeve in combination with the body portion having a specific gravitygreater than the heavy phase of blood.

7. The piston of claim 6 wherein an axial recess is formed in the bodyportion, the closed end of the recess defining an end wall portionhaving the pressure responsive valve means formed therein.

8. The piston of claim 7 wherein the end wall portion is formed of anelastomeric material having at least one aperture formed therein, saidaperture being normally closed where there is a minimum pressuredifferential on the two sides of the end wall and which automaticallyopens in response to a substantial pressure differential.

9. The piston of claim 6 wherein the body portion of said piston isformed having a filter means associated therewith and in fluidcommunication with said pressure responsive valve means whereby saidfilter means is adapted to remove particulate material from the lightphase as the piston moves downwardly therethrough.

10. The invention in accordance with claim 4, wherein a plurality ofspaced annular sealing rings are on the periphery of the piston and insealing engagement with the interior of the container.

11. The invention in accordance with claim 4, wherein the valve means isindependent of the piston sealing means.

12. A method for the sealed separation of blood into its light phase ofserum or plasma and its heavy phase of cellular portion with a sealedcontainer assembly comprising:

a. introducing blood in said assembly through a selfsealing closuremounted in one end of the assembly remote from a piston slidably mountedin sealing engagement with the inner surface of the container and saidpiston having pressure responsive valve means mounted thereon with thepiston having a greater specific gravity than the red cells-of blood andbeing disposed above the blood to be separated; 1

b. subjecting the assembly to differing amounts of centrifugal forcewhereby with moderate centrifugal force the pressure responsive valvemeans is normally closed and there is a minimum of pressure differentialon the two sides of the valve means and with substantially increasedcentrifugal force the valve means automatically opens in response tosubstantial pressure differential which enables the piston to movedownwardly through the light phase while the light phase passes upthrough the valve means; and

c. stopping the piston by applying a restraining force by a stopinteriorly of the container and at a point above the separated heavyphase and automatically shifting the pressure responsive valve meansfrom an open condition to a closed condition.

13. The method of separating blood into its light phase, consisting ofserum or plasma, and its heavy phase, consisting of concentrated redcells, comprising the steps of:

a. introducing the blood sample into a sealed and evacuated bloodcontainer comprising a double ended tube sealed at each end by anelastomeric closure and with a slidable piston adjacent the closureopposite the closure through which the blood is introduced;

b. centrifuging the blood container first at a moderate speed and withthe end of the blood container with the piston uppermost so that thepiston does not slide downwardly but the blood does separate into itsheavy phase at the bottom and the light phase at the top; 5

c. then centrifuging the blood container at a substantially increasedspeed whereby the slidable piston, having a specific gravitysubstantially greater than either the serum or red cells, overcomes thesliding and sealing friction and moves downwardly thereby increasing thehydrostatic pressure of the liquid ahead of it, this increased pressureautomatically opening a normally closed valve means which is associatedwith the piston, which allows the light phase to pass up through thevalve means and permits the piston to descend to a mechanical stopmeans;

d. stopping the descent of the piston by the stop means despite thecontinued action of centrifugal force, and after stopping the piston,the light phase liquid continues to flow upwardly through the valvemeans thereby diminishing the hydrostatic pressure ahead of the pistonuntil the differential pressure is so diminished that the valve meapsautomatically closes again, thereby providing a permanent sealed barrierbetween the light phase and the heavy phase of the blood.

14. A fluid separator assembly capable of separating blood into itscomponent parts of plasma or serum and cellular portion comprising:

a. a container for receiving blood and having at least one open endwhich is adapted to receive a closure for sealing the open end of thecontainer;

b. a piston having a specific gravity relatively greater than thecellular portion of the blood and slidably mounted in the container andhaving means on an outer surface thereof for sealing engagement with theinner surface of the container;

d. pressure responsive valve means associated with the piston, saidvalve means being normally closed and being adapted to automaticallyopen when subjected to a predetermined pressure when the piston a.introducing blood through a first closure at one end of a tubularcontainer having a second closure at its opposite end, with a slidablesealing piston adjacent said second closure and having a specificgravity relatively greater than the cellular portion of blood, theinflowing blood filling a first chamber consisting of the space betweenthe first closure,

the interior surface of the container, and the piston;

ble of separating blood into its component parts of plasma or serum andcellular portion comprising:

a. a tubular container having two open ends;

b. resilient closure means adapted to close said ends,

b. subjecting the container of blood to moderate centrifugal forcewhereby the heavy cellular portion of the blood is precipitateddownwardly and the lighter plasma or serum is displaced upwardly withinwith at least one of said closure means capable of the first chamber,while the piston stays in the being penetrated by a cannula for fillingwith upper portion of the container; blood; c. then subjecting thecontainer to increased centrifuc. a slidable piston having a specificgravity relatively g force whereby the Pitton is eaused to Slide greaterthan the cellular portion of blood and being downwardly and the PlasmaSerum flows P into in sealed relation with the inside surface of saidasecond chfimbel' Created by thed wnward move container, said pistonbeing located initially adjameht of the Plstoh and p g the Space centthe closure opposite to that through which the tween the piston, theseeohd closure, and the intercannula may penetrate, the space within thetube Surface of the eohtamer; and and between the penetrable closure andthe piston e lh the Plsteh eutomatleauy y p forming a first chamber forreceiving blood from means interlorly of the container above thecellular the cannula; portion of the blood and permanently sealing thed. said slidable piston being adapted to remain in the Plston, wherebythe q hghter and heavler P upper part of the container while moderatecentrif- Ses hfivmg been l separate chamberet and ugal force is used toprecipitate the cellular portion the of contammatlon f h l'ght Phase m tof the blood with the displaced plasma or Serum second chamber has beenel minated by prevent ng flowing into the upper portion of the firstchamber; any blood cellular matena] from ever havmg e. the piston beingfurther adapted, when subjected passed through the Second closure; orthrough the to increased centrifugal force, to slide downwardly i zggffrgfizgd tllggg si zg iftggwl ca 3 through the plasma or serum thusforming a second bl g t bl to com onem gms of chamber within the tubularcontainer and between 3 5 Separa mg d n I p the piston and the closureopposite to the closure p eeme or e ee PC g g f h previously penetratedby the cannula, said second adcomgmer f g i e open en w 1e chamber beingfilled with plasma or serum only; I s refiewe s e e eeperanon f. thepiston being further adapted to automatically b ""91 lg e an e eavy t thth stop and form a permanent sealed barrier in the 40 i en ev.mg j greeer d plasma or serum slightly above the heavy phase, ee u 'f" pemen e 00e e y f i t e without any blood cellular material ever passing eememerso that when Sale eememer through the closure opposite the closure pene-Li i gglii g g gz is gzz z g ile e pi tla n g es g li fgfig e g t f zgggyz jiei i i l adapted to slide in the container and eventually lo-Hula! ma cate near the interface of the light and heavy phase; z m i ifigg zz 1323: :i Ce c. said piston having means on an outer surface ineria o g. stop means for cooperating with the piston in aszfi izfi ggwlth an mner surface of the ig l ge the cellular pomen of the d. meansassociated with said piston for permitting oo rom e lqui f l S rum n 16.A method for the sealed separation of blood into 2 ;22 3 fifig r g forpp g the its light phase of e j or Serum and heavy phase piston near theinterface and at a predetermined of cellular portion within a sealedcontainer assembly 7 distance from one of the ends of the container.comprising: mm l, t

UNITED STATES PATENT OFFICE CERTIFICATE OF FCTION Patent No. 3,779, 383Dated December 18, 1973 Inven t Waldemar A. Avres It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

IN THE CLAIMS:

Claim 10, line 1, change the numeral "4" to 6 Claim ll, line 1, changethe numeral "4 to 6 Claim 15, line 47, the word "eliminate" sheuld beeliminated Signed and sealed this 9th day of July 1974 (S AL) Attest:

MCCOY M. GIBSON, JR. 0. MARSHALL D'ANN Attesting Officer Commissioner ofPatents USCOMM-DC 60376-P69 us, GOVERNMENT PRINTING OFFICE: I989 0-366-3

2. The self-contained fluid separator of claim 1 wherein the pistonincludes a rigid tubular sleeve mounted in a generally tubular outerbody portion formed of an elastomer and having at least one sealing ringon its outer portion for sealing engagement with the inner walls of thecontainer and a diaphragm forming a wall across one end of the generallytubular elastomeric sleeve and having apertures formed therein which arenormally closed but which automatically open when subjected to asubstantial pressure differential on the opposite sides of thediaphragm.
 3. The self-contained fluid separator of claim 1 wherein thestop means on the container is an annular groove interposed between theends of the container forming an annular constriction of the innersurface of the container so that said piston is prevented from passingthe stop means when subjected to centrifugal forces.
 4. The invention inaccordance with claim 1, wherein a plurality of spaced annular sealingrings are on the periphery of the piston and in sealing engagement withthe interior of the container.
 5. The invention in accordance with claim1, wherein the valve means is independent of the piston sealing means.6. A piston adapted for use for separating fluid into a light phase anda heavy phase in a self-contained fluid separating assembly comprising:a. a body portion having sealing means formed on its outer peripheralwalls for maintaining sealing engagement with the inner walls of thefluid separator assembly; b. a rigid tubular sleeve mounted in the bodyportion of said piston and having an interference fit and pressureresponsive valve means mounted on the piston which is normally closedwhen there is a minimum of pressure differential on the surfaces of thevalve means and which opens automatically in response to a substantialpressure differential so that when the container is subjected tomoderate centrifugal force the fluid separates into its light phase andheavy phase and when the container is subjected to increased centrifugalforce the valve means automatically opens with the light phase passingthrough the valve means enabling the piston to move down through thelight phase while retaining sealing engagement with the inner surfacesof the container, the rigid tubular sleeve in combination with the bodyportion having a specific gravity greater than the heavy phase of blood.7. The piston of claim 6 wherein an axial recess is formed in the bodyportion, the closed end of the recess defining an end wall portionhaving the pressure responsive valve means formed therein.
 8. The pistonof claim 7 wherein the end wall portion is formed of an elastomericmaterial having at least one aperture formed therein, said aperturebeing normally closed where there is a minimum pressure differential onthe two sides of the end wall and which automatically opens in responseto a substantial pressure differential.
 9. The piston of claim 6 whereintbe body portion of said piston is formed having a filter meansassociated therewith and in fluid communication with said pressureresponsive valve means whereby said filter means is adapted to removeparticulate material from the light phase as the piston moves downwardlytherethrough.
 10. The invention in accordance with claim 4, wherein aplurality of spaced annular sealing rings are on the periphery of thepiston and in sealing engagement with the interior of the container. 11.The invention in accordance with claim 4, wherein the valve means isindependent of the piston sealing means.
 12. A method for the sealedseparation of blood into its light phase of serum or plasma and itsheavy phase of cellular portion with a sealed container assemblycomprising: a. introducing blood in said assembly through a self-sealingclosure mounted in one end of the assembly remote from a piston slidablymounted in sealing engagement with the inner surface of the containerand said piston having pressure responsive valve means mounted thereonwith the piston having a greater specific gravity than the red cells ofblood and being disposed above the blood to be separated; b. subjectingthe assembly to differing amounts of centrifugal force whereby withmoderate centrifugal force the pressure responsive valve means isnormally closed and there is a minimum of pressure differential on thetwo sides of the valve means and with substantially increasedcentrifugal force the valve means automatically opens in response tosubstantial pressure differential which enables the piston to movedownwardly through the light phase while the light phase passes upthrough the valve means; and c. stopping the piston by applying arestraining force by a stop interiorly of the container and at a pointabove the separated heavy phase and automatically shifting the pressureresponsive valve means from an open condition to a closed condition. 13.The method of separating blood into its light phase, consisting of serumor plasma, and its heavy phase, consisting of concentrated red cells,comprising the steps of: a. introducing the blood sample into a sealedand evacuated blood container comprising a double ended tube sealed ateach end by an elastomeric closure and with a slidable piston adjacentthe closure opposite the closure through which the blood is introduced;b. centrifuging the blood container first at a moderate speed and withthe end of the blood container with the piston uppermost so that thepiston does not slide downwardly but the blood does separate into itsheavy phase at the bottom and the light phase at the top; c. thencentrifuging the blood container at a substantially increased speedwhereby the slidable piston, having a specific gravity substantiallygreater than either the serum or red cells, overcomes the sliding andsealing friction and moves downwardly thereby increasing the hydrostaticpressure of the liquid ahead of it, this increased pressureautomatically opening a normally closed valve means which is associatedwith the piston, which allows the light phase to pass up through thevalve means and permits the piston to descend to a mechanical stopmeans; d. stopping the descent of the piston by the stop means despitethe continued action of centrifugal force, and after stopping thepiston, the light phase liquid continues to flow upwardly through thevalve means thereby diminishing the hydrostatic pressure ahead of thepiston until the differential pressure is so diminished that the valvemeans automatically closes again, thereby providing a permanent sealedbarrier between the light phase and the heavy phase of the blood.
 14. Afluid separator assembly capable of separating blood into its componentparts of plasma or serum and cellular portion comprising: a. a containerfor receiving bloOd and having at least one open end which is adapted toreceive a closure for sealing the open end of the container; b. a pistonhaving a specific gravity relatively greater than the cellular portionof the blood and slidably mounted in the container and having means onan outer surface thereof for sealing engagement with the inner surfaceof the container; d. pressure responsive valve means associated with thepiston, said valve means being normally closed and being adapted toautomatically open when subjected to a predetermined pressure when thepiston is slidably moving within the container and which automaticallyclose when the piston ceases movement to isolate a substantial amount ofthe plasma or serum from the cellular portion; and e. stop meansinteriorally of the container for cooperating with the piston inassuring the isolation of the light phase of the plasma or serum fromthe cellular portion.
 15. A self-contained fluid separator assembly,capable of separating blood into its component parts of plasma or serumand cellular portion comprising: a. a tubular container having two openends; b. resilient closure means adapted to close said ends, with atleast one of said closure means capable of being penetrated by a cannulafor filling with blood; c. a slidable piston having a specific gravityrelatively greater than the cellular portion of blood and being insealed relation with the inside surface of said container, said pistonbeing located initially adjacent the closure opposite to that throughwhich the cannula may penetrate, the space within the tube and betweenthe penetrable closure and the piston forming a first chamber forreceiving blood from the cannula; d. said slidable piston being adaptedto remain in the upper part of the container while moderate centrifugalforce is used to precipitate the cellular portion of the blood with thedisplaced plasma or serum flowing into the upper portion of the firstchamber; e. the piston being further adapted, when subjected toincreased centrifugal force, to slide downwardly through the plasma orserum thus forming a second chamber within the tubular container andbetween the piston and the closure opposite to the closure previouslypenetrated by the cannula, said second chamber being filled with plasmaor serum only; f. the piston being further adapted to automatically stopand form a permanent sealed barrier in the plasma or serum slightlyabove the heavy phase, without any blood cellular material ever passingthrough the closure opposite the closure penetrated by the cannula, orthrough the second chamber, or through the piston, whereby any risk ofcontamination of plasma or serum by the cellular material of the bloodis eliminate; and g. stop means for cooperating with the piston inassuring the isolation of the cellular portion of the blood from theliquid.
 16. A method for the sealed separation of blood into its lightphase of plasma or serum and its heavy phase of cellular portion withina sealed container assembly comprising: a. introducing blood through afirst closure at one end of a tubular container having a second closureat its opposite end, with a slidable sealing piston adjacent said secondclosure and having a specific gravity relatively greater than thecellular portion of blood, the inflowing blood filling a first chamberconsisting of the space between the first closure, the interior surfaceof the container, and the piston; b. subjecting the container of bloodto moderate centrifugal force whereby the heavy cellular portion of theblood is precipitated downwardly and the lighter plasma or serum isdisplaced upwardly within the first chamber, while the piston stays inthe upper portion of the container; c. then subjecting the container toincreased centrifugal force whereby the piston is caused to slidedownwardly and the plasma or serum flows up into a second chambercreated by the downward movement of the piston and comprising the spAcebetween the piston, the second closure, and the interior surface of thecontainer; and d. then stopping the piston automatically by stop meansinteriorly of the container above the cellular portion of the blood andpermanently sealing the piston, whereby the blood, lighter and heavierphases having been sealed in separate chambers, and the risk ofcontamination of the light phase in the second chamber has beeneliminated by preventing any blood cellular material from ever havingpassed through the second closure, or through the second chamber, orthrough the piston.
 17. A self-contained fluid separator assembly,capable of separating blood into its component parts of plasma or serumand cellular portion, comprising: a. a container having at least oneopen end which is adapted to receive blood for subsequent separationinto a light phase and a heavy phase; b. a piston having a specificgravity greater than the cellular portion of blood slidably mounted inthe container so that when said container is subjected to centrifugalforce the blood separates into its light phase and heavy phase, and thepiston is adapted to slide in the container and eventually locate nearthe interface of the light and heavy phase; c. said piston having meanson an outer surface in sealing engagement with an inner surface of thecontainer; d. means associated with said piston for permitting passageof plasma or serum; and e. stop means within the container for stoppingthe piston near the interface and at a predetermined distance from oneof the ends of the container.